我听说在活动中添加过多代码不是最佳实践，因此在我的项目中，活动中包含过多代码，现在我正尝试将其传递给另一个片段。这是我的活动：
package com.example.gio.autostop;
import android.Manifest;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.location.Geocoder;
import android.location.Location;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.toolbox.Volley;
import com.google.android.gms.location.LocationListener;
import android.location.LocationManager;
import android.os.Build;
import android.os.Handler;
import android.os.ResultReceiver;
import android.provider.Settings;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AlertDialog;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.net.NetworkInterface;
import java.text.DateFormat;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.List;
public class MapsActivity extends FragmentActivity implements LocationListener,
GoogleApiClient.OnConnectionFailedListener, OnMapReadyCallback, GoogleMap.OnMyLocationButtonClickListener,
GoogleApiClient.ConnectionCallbacks {
public int permissionRequestCounter;
public GoogleApiClient mGoogleApiClient;
public Boolean startedLocationUpdate;
public LocationRequest locationRequest;
public Location mCurrentLocation;
public LocationManager mLocationManager;
public final static int MILISECONDS_PER_SECOND = 1000;
public final static int REQUEST_FINE_LOCATION = 0;
public final static int MINUTE = 60 * MILISECONDS_PER_SECOND;
protected String mLastUpdateTime;
protected final static String REQUESTING_LOCATION_UPDATES_KEY = "requesting-location-updates-key";
protected final static String LOCATION_KEY = "location-key";
protected static final String ADDRESS_REQUESTED_KEY = "address-request-pending";
protected static final String LOCATION_ADDRESS_KEY = "location-address";
protected static final String TAG = "main-activity";
protected boolean mAddressRequested;
protected String mAddressOutput;
protected TextView mLocationAddressTextView;
private AddressResultReceiver mResultReceiver;
private GoogleMap mMap;// Might be null if Google Play services APK is not available.
private ProgressBar mProgressBar;
private Button checkInButton,checkOutButton;
private ArrayList<Marker> markerCollection = new ArrayList<>();
private Marker markerForDeletion;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_maps);
setUpMapIfNeeded();
checkInButton = (Button) findViewById(R.id.button2);
checkOutButton=(Button)findViewById(R.id.button3);
SupportMapFragment mapFragment =
(SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
startedLocationUpdate = false;
permissionRequestCounter = 0;
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
locationRequest = new LocationRequest();
locationRequest.setInterval(MINUTE);
locationRequest.setFastestInterval(15 * MILISECONDS_PER_SECOND);
locationRequest.setPriority(com.google.android.gms.location.LocationRequest.PRIORITY_HIGH_ACCURACY);
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
checkGps();
}
mResultReceiver = new AddressResultReceiver(new Handler());
mProgressBar = (ProgressBar) findViewById(R.id.progress_bar);
mAddressRequested = false;
mAddressOutput = "";
mLocationAddressTextView = (TextView) findViewById(R.id.address);
updateUIWidgets();
deviceUniqueNumber();
updateValuesFromBundle(savedInstanceState);
checkInButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
checkInCurrentPosition();
checkInButton.setClickable(false);
checkOutButton.setClickable(true);
}
});
checkOutButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
deletePosition();
markerForDeletion.remove();
checkOutButton.setClickable(false);
checkInButton.setClickable(true);
}
});
checkOutButton.setClickable(false);
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
Log.i(TAG, "Connection failed: ConnectionResult.getErrorCode() = " + connectionResult.getErrorCode());
}
@Override
protected void onStart() {
super.onStart();
mGoogleApiClient.connect();
}
@Override
protected void onResume() {
super.onResume();
setUpMapIfNeeded();
if (mGoogleApiClient.isConnected() && !startedLocationUpdate)
startLocationUpdates();
}
@Override
public void onConnected(Bundle bundle) {
if (!startedLocationUpdate)
startLocationUpdates();
if (mCurrentLocation != null) {
if (!Geocoder.isPresent()) {
Toast.makeText(this, R.string.no_geocoder_available, Toast.LENGTH_SHORT).show();
return;
}
if (mAddressRequested) {
startIntentService();
}
}
}
@Override
public void onConnectionSuspended(int i) {
mGoogleApiClient.connect();
}
@Override
protected void onStop() {
super.onStop();
mGoogleApiClient.disconnect();
}
private void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (mMap == null) {
// Try to obtain the map from the SupportMapFragment.
mMap = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
.getMap();
// Check if we were successful in obtaining the map.
if (mMap != null) {
setUpMap();
}
}
}
protected void stopLocationUpdates() {
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
startedLocationUpdate = false;
}
@Override
protected void onPause() {
super.onPause();
if (mGoogleApiClient.isConnected() && startedLocationUpdate)
stopLocationUpdates();
}
private void startLocationUpdates() {
if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP) {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, locationRequest, MapsActivity.this);
startedLocationUpdate = true;
} else {
if (permissionRequestCounter == 0) {
requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_FINE_LOCATION);
permissionRequestCounter++;
}
}
}
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
mMap.setOnMyLocationButtonClickListener(this);
enableMyLocation();
}
public void enableMyLocation() {
if (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP) {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
// Permission to access the location is missing.
if (permissionRequestCounter == 0) {
requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, REQUEST_FINE_LOCATION);
permissionRequestCounter++;
}
} else if (mMap != null) {
// Access to the location has been granted to the app.
mMap.setMyLocationEnabled(true);
}
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
switch (requestCode) {
case REQUEST_FINE_LOCATION: {
if (grantResults.length == 1
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
enableMyLocation();
checkGps();
} else {
Toast.makeText(MapsActivity.this, "Permission was blocked", Toast.LENGTH_SHORT).show();
}
}
}
}
@Override
public boolean onMyLocationButtonClick() {
checkGps();
return false;
}
public void checkGps() {
final LocationManager manager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
if (!manager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
buildAlertMessageNoGps();
}
}
@Override
public void onLocationChanged(Location location) {
mCurrentLocation = location;
mLastUpdateTime = DateFormat.getTimeInstance().format(new Date());
fetchAddressHandler();
}
private void setUpMap() {
Response.Listener<String> responseListener = new Response.Listener<String>() {
@Override
public void onResponse(String s) {
try {
JSONObject jsonResponse = new JSONObject(s);
boolean success = jsonResponse.getBoolean("success");
if (success) {
JSONArray jsonArray = jsonResponse.getJSONArray("data");
JSONObject jsonObject;
for (int i = 0; i < jsonArray.length(); i++) {
jsonObject = jsonArray.getJSONObject(i);
String mac = jsonObject.getString("mac");
String android_id = jsonObject.getString("android_id");
Double latitude = jsonObject.getDouble("latitude");
Double longitude = jsonObject.getDouble("longitude");
if (!isMarkerOnArray(markerCollection, latitude, longitude))
markerCollection.add(mMap.addMarker(new MarkerOptions().position(new LatLng(latitude, longitude))));
}
} else {
AlertDialog.Builder builder = new AlertDialog.Builder(MapsActivity.this);
builder.setMessage("Downloading position failed")
.setNegativeButton("retry", null)
.create()
.show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
};
DownloadPosition downloadPosition = new DownloadPosition(responseListener);
RequestQueue queue = Volley.newRequestQueue(MapsActivity.this);
queue.add(downloadPosition);
}
private boolean isMarkerOnArray(ArrayList<Marker> array, Double Latitude, Double Longitude) {
Marker current;
for (int c = 0; c < array.size(); c++) {
current = array.get(c);
if ((current.getPosition().latitude == Latitude) && (current.getPosition().longitude == Longitude))
return true;
}
return false;
}
private void buildAlertMessageNoGps() {
final AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setMessage("Your GPS seems to be disabled, do you want to enable it?")
.setCancelable(false)
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(@SuppressWarnings("unused") final DialogInterface dialog, @SuppressWarnings("unused") final int id) {
startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
}
})
.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(final DialogInterface dialog, @SuppressWarnings("unused") final int id) {
dialog.cancel();
}
});
final AlertDialog alert = builder.create();
alert.show();
}
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
savedInstanceState.putBoolean(REQUESTING_LOCATION_UPDATES_KEY, startedLocationUpdate);
savedInstanceState.putParcelable(LOCATION_KEY, mCurrentLocation);
savedInstanceState.putBoolean(ADDRESS_REQUESTED_KEY, mAddressRequested);
savedInstanceState.putString(LOCATION_ADDRESS_KEY, mAddressOutput);
super.onSaveInstanceState(savedInstanceState);
}
private void updateValuesFromBundle(Bundle savedInstanceState) {
if (savedInstanceState != null) {
if (savedInstanceState.keySet().contains(REQUESTING_LOCATION_UPDATES_KEY))
startedLocationUpdate = savedInstanceState.getBoolean(REQUESTING_LOCATION_UPDATES_KEY);
if (savedInstanceState.keySet().contains(LOCATION_KEY))
mCurrentLocation = savedInstanceState.getParcelable(LOCATION_KEY);
if (savedInstanceState.keySet().contains(ADDRESS_REQUESTED_KEY)) {
mAddressRequested = savedInstanceState.getBoolean(ADDRESS_REQUESTED_KEY);
}
if (savedInstanceState.keySet().contains(LOCATION_ADDRESS_KEY)) {
mAddressOutput = savedInstanceState.getString(LOCATION_ADDRESS_KEY);
displayAddressOutput();
}
}
}
private void updateUIWidgets() {
if (mAddressRequested) {
mProgressBar.setVisibility(ProgressBar.VISIBLE);
} else {
mProgressBar.setVisibility(ProgressBar.GONE);
}
}
public void fetchAddressHandler() {
if (mGoogleApiClient.isConnected() && mCurrentLocation != null) {
startIntentService();
}
mAddressRequested = true;
updateUIWidgets();
}
private void startIntentService() {
Intent intent = new Intent(this, FetchAddressIntentService.class);
intent.putExtra(Constants.RECEIVER, mResultReceiver);
intent.putExtra(Constants.LOCATION_DATA_EXTRA, mCurrentLocation);
startService(intent);
}
protected void displayAddressOutput() {
mLocationAddressTextView.setText(mAddressOutput);
}
public void checkInCurrentPosition() {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
return;
}
mLocationManager = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
Location locationGPS = mLocationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
Location locationNet = mLocationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
Location location;
long GPSLocationTime = 0;
if (null != locationGPS) { GPSLocationTime = locationGPS.getTime(); }
long NetLocationTime = 0;
if (null != locationNet) {
NetLocationTime = locationNet.getTime();
}
if ( 0 < GPSLocationTime - NetLocationTime ) {
location=locationGPS;
}
else {
location=locationNet;
}
LatLng newLatLng = new LatLng(location.getLatitude(), location.getLongitude());
markerForDeletion=mMap.addMarker(new MarkerOptions().position(newLatLng).title(newLatLng.toString()));
String deviceId = Settings.Secure.getString(this.getContentResolver(), Settings.Secure.ANDROID_ID);
Positions position=new Positions(newLatLng.latitude,newLatLng.longitude,getWifiMacAddress(),deviceId);
Response.Listener<String> responseListener= new Response.Listener<String>() {
@Override
public void onResponse(String s) {
try {
JSONObject jsonResponse= new JSONObject(s);
boolean success=jsonResponse.getBoolean("success");
if(!success){
AlertDialog.Builder builder=new AlertDialog.Builder(MapsActivity.this);
builder.setMessage("uploading position failed")
.setNegativeButton("retry",null)
.create()
.show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
};
UploadPosition upload=new UploadPosition(position,responseListener);
RequestQueue queue= Volley.newRequestQueue(MapsActivity.this);
queue.add(upload);
}
public void deletePosition(){
String deviceId = Settings.Secure.getString(this.getContentResolver(), Settings.Secure.ANDROID_ID);
String mac=getWifiMacAddress();
Response.Listener<String> responseListener = new Response.Listener<String>(){
@Override
public void onResponse(String s) {
try {
JSONObject jsonResponse= new JSONObject(s);
boolean success=jsonResponse.getBoolean("success");
if(!success){
AlertDialog.Builder builder=new AlertDialog.Builder(MapsActivity.this);
builder.setMessage("uploading position failed")
.setNegativeButton("retry",null)
.create()
.show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
};
DeletePosition delete=new DeletePosition(mac,deviceId,responseListener);
RequestQueue queue=Volley.newRequestQueue(MapsActivity.this);
queue.add(delete);
}
class AddressResultReceiver extends ResultReceiver {
private int CREATOR;
public AddressResultReceiver(Handler handler) {
super(handler);
}
@Override
protected void onReceiveResult(int resultCode, Bundle resultData) {
mAddressOutput = resultData.getString(Constants.RESULT_DATA_KEY);
displayAddressOutput();
mAddressRequested = false;
updateUIWidgets();
super.onReceiveResult(resultCode, resultData);
}
}
public void deviceUniqueNumber(){
String deviceId = Settings.Secure.getString(this.getContentResolver(), Settings.Secure.ANDROID_ID);
Toast.makeText(this,deviceId+" "+getWifiMacAddress(),Toast.LENGTH_SHORT).show();
}
public static String getWifiMacAddress() {
try {
String interfaceName = "wlan0";
List<NetworkInterface> interfaces = Collections.list(NetworkInterface.getNetworkInterfaces());
for (NetworkInterface intf : interfaces) {
if (!intf.getName().equalsIgnoreCase(interfaceName)){
continue;
}
byte[] mac = intf.getHardwareAddress();
if (mac==null){
return "";
}
StringBuilder buf = new StringBuilder();
for (byte aMac : mac) {
buf.append(String.format("%02X:", aMac));
}
if (buf.length()>0) {
buf.deleteCharAt(buf.length() - 1);
}
return buf.toString();
}
} catch (Exception ex) {
Log.i("getWifiMacAddress","exception in getWifiMacAddress");
}
return "";
}
}
所以首先我创建了这个片段，并在其中转移了一些代码：
package com.example.gio.autostop;
import android.support.v4.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.ResultReceiver;
import android.widget.ProgressBar;
import android.widget.TextView;
public class GettingAddressFragment extends Fragment{
private AddressResultReceiver mResultReceiver;
private ProgressBar mProgressBar;
protected boolean mAddressRequested;
protected String mAddressOutput;
protected TextView mLocationAddressTextView;
@Override
public void onCreate( Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mResultReceiver = new AddressResultReceiver(new Handler());
mProgressBar = (ProgressBar) getView().findViewById(R.id.progress_bar);
mAddressRequested = false;
mAddressOutput = "";
mLocationAddressTextView = (TextView) getView().findViewById(R.id.address);
updateUIWidgets();
}
class AddressResultReceiver extends ResultReceiver {
private int CREATOR;
public AddressResultReceiver(Handler handler) {
super(handler);
}
@Override
protected void onReceiveResult(int resultCode, Bundle resultData) {
mAddressOutput = resultData.getString(Constants.RESULT_DATA_KEY);
displayAddressOutput();
mAddressRequested = false;
updateUIWidgets();
super.onReceiveResult(resultCode, resultData);
}
}
protected void displayAddressOutput() {
mLocationAddressTextView.setText(mAddressOutput);
}
private void startIntentService() {
Intent intent = new Intent(this, FetchAddressIntentService.class);
intent.putExtra(Constants.RECEIVER, mResultReceiver);
intent.putExtra(Constants.LOCATION_DATA_EXTRA, mCurrentLocation);
startService(intent);
}
public void fetchAddressHandler() {
if (mGoogleApiClient.isConnected() && mCurrentLocation != null) {
startIntentService();
}
mAddressRequested = true;
updateUIWidgets();
}
private void updateUIWidgets() {
if (mAddressRequested) {
mProgressBar.setVisibility(ProgressBar.VISIBLE);
} else {
mProgressBar.setVisibility(ProgressBar.GONE);
}
}
}
但是某些变量也必须处于活动状态，例如：mAddressRequested和mAddressOutput。这些变量导致活动错误，因为我将它们分段传输。startIntentService，fetchAddressHandler，displayAddressOutput-活动中也需要这些方法。所以我的问题是在这种情况下我该怎么办？我如何处理这些变量和方法，这些变量和方法是我在片段中转移的，但活动中也需要它们？
您可以将变量从活动传递到片段，反之亦然。从活动实例化片段时，传递任何参数：
Bundle args = new Bundle();
args.putParcelable("tag", variableName);
GettingAddressFragment frag = new GettingAddressFragment();
frag.setArguments(args);
然后在您的片段中：
Bundle args = getArguments();
variable = args.getParcelable("tag");
如果您从片段开始活动，则可以将变量传递给intent，就像在其他任何地方一样：
Intent myIntent = new Intent(this, MapsActivity.class);
myIntent.putExtra("tag", variable);
startActivity(myIntent);
然后在您的活动中：
Intent search = getIntent();
variable = search.getParcelableExtra("tag");
除了Parcelable对象，您还可以传递int，char等。
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